The main objective of this project is to investigate the ultrastructure and physiology of the crustacean stretch receptor organ. The functions of the axoaxonic synapse between two inhibitory nerve terminals on the receptor neuron will be studied. We also plan to study stretch-induced structural changes in the dendrites of the sensory neuron, where the generator potential occurs. In addition, the membrane fine structure of the inhibitory synapses on the receptor neuron and the drug effects on the generator potential will be studied. We will use electron microscopical, microelectrophysiological and freeze-fracture techniques. The other objective of the project is to investigate fine structural changes in the newly-formed neuromuscular junctions prepared by tissue culture. We will use electron microscopical, electrophysiological, freeze-fracture and tissue culture methods.